The invention relates to a semiconductor device, comprising a semiconductor body with a bipolar transistor which consists of electrically parallel transistor structures at least a number of which have different values of emitter series resistance, said transistor comprising a collector zone which is formed by a semiconductor region of a first conductivity type, a base zone of the second, opposite conductivity type which adjoins both the collector zone and a surface of the semiconductor body, base metallization contacting the base zone via a number of base contact windows in an insulating layer at said surface, and an emitter zone of the first conductivity type which is formed in the base zone and which comprises a number of active emitter regions which are situated near the base contact windows and which constitute the emitters of the transistor structures, said emitter zone further comprising a number of emitter contact regions contacted by an emitter metallization via emitter contact windows in the insulating layer, and a number of emitter connection regions which interconnect the emitter contact regions and the active emitter regions.
A semiconductor device having these features is particularly suitable for use in integrated circuits. By a suitable proportioning of the emitter series resistances in accordance with the circuit, a uniform temperature distribution can be obtained during operation in the part of the semiconductor body which is occupied by the transistor. The power handling capability of the bipolar transistor, limited by local overheating, can thus be improved.
A semiconductor device having these features is described in W. German Patent Application DE-OS 2625989, corresponding to U.S. Pat. No. 4,072,979, in which the various emitter series resistances of the subtransistors are obtained by imparting different dimensions to the emitter connection regions of the transistor structures.
It is a drawback of this known semiconductor device that, in order to realize a desirable distribution of the emitter series resistance values across the surface occupied by the bipolar transistor, a particular emitter zone configuration is required, that is to say an emitter diffusion mask which has been constructed in a given manner. Because the dissipation of heat of the transistor in an integrated circuit is dependent on its position within the integrated circuit, different emitter diffusion masks may be required in order to include the transistor in different integrated circuits.